Project Summary/Abstract Our long-term goal is to elucidate biobehavioral mechanisms contributing to distressing symptoms in hematopoietic cell transplantation (HCT) survivors for the development and implementation of targeted therapies to improve quality of life (QOL) in this patient population. Due to treatment advances, HCT is becoming an increasingly viable option for individuals with life-threatening hematologic disorders and the number of survivors is increasing. Thus, survivorship issues such as distressing symptoms of neurocognitive dysfunction, fatigue, anxiety and depressive symptoms, and pain collectively labeled as ?psychoneurologic? (PN) symptoms are a major issue. To date, little is known about the suspected shared biological underpinnings influencing PN symptoms. Inflammation is a generally accepted mechanism of PN symptoms in multiple chronic illnesses, including cancer. Emerging evidence of gut microbiota, via the microbiota-gut-brain-axis, as a potential pathway for the initiation of an inflammatory response may lead to innovative strategies, including diet and nutrition strategies to reduce inflammation. Understanding the interplay among diet and the gut microbiota with inflammation and PN symptoms may provide information leading to targeted self-management strategies to mitigate PN symptoms in individuals following HCT. The specific aims of this study are to: 1) Evaluate study feasibility of data collection, acceptability of study procedures including recruitment and retention, and missingness of data, 2) Characterize the strength of the associations (effect sizes) at baseline (14-7 days prior to hospital admission for HCT conditioning) among patient factors, PN symptoms, inflammation, GM and diet and 3) Estimate associations (effect sizes) and models for change over time (14-7 days prior to hospital admission for HCT conditioning, 30 and 100 days after HCT) for: a) Patient factors and PN symptoms with Inflammation b) Patient factors, PN symptoms and Inflammation with GM c) Patient factors, PN symptoms, Inflammation and GM with Diet d) Patient factors, Diet, GM and Inflammation with PN symptoms. To achieve these aims, we will longitudinally examine 50 adult (> 18 years of age) HCT recipients recruited from the University of Florida Bone Marrow Transplant Center. We will characterize patient factors (age, sex, race, ethnicity, BMI, lifestyle habits, and clinical factors [cancer diagnosis, conditioning regimen, type of transplant]); systemic inflammation (cytokines and C-reactive protein); gut microbiota (richness and diversity); diet (consumption of macronutrients); and PN symptoms (neurocognitive dysfunction, fatigue, anxiety, depression, and pain) at baseline (two weeks or less prior to HCT), 30 and 100 days following HCT. State-of-the-art technology will be used to analyze the biological samples and innovative Bayesian statistical methodologies will be used to test the models of the study variables. This knowledge is critical to provide a foundation for developing a targeted diet self-management intervention to address this major survivorship issue and improve QOL for HCT recipients.